/*
  KeePass Password Safe - The Open-Source Password Manager
  Copyright (C) 2003-2017 Dominik Reichl <dominik.reichl@t-online.de>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

using System;
using System.Diagnostics;
using System.Text;

using KeePassLib.Cryptography;
using KeePassLib.Security;
using KeePassLib.Utility;

namespace KeePassLib.Keys
{
  /// <summary>
  /// Master password / passphrase as provided by the user.
  /// </summary>
  public sealed class KcpPassword : IUserKey
  {
    private ProtectedString m_psPassword;
    private ProtectedBinary m_pbKeyData;

    /// <summary>
    /// Get the password as protected string.
    /// </summary>
    public ProtectedString Password
    {
      get { return m_psPassword; }
    }

    /// <summary>
    /// Get key data. Querying this property is fast (it returns a
    /// reference to a cached <c>ProtectedBinary</c> object).
    /// If no key data is available, <c>null</c> is returned.
    /// </summary>
    public ProtectedBinary KeyData
    {
      get { return m_pbKeyData; }
    }

    public uint GetMinKdbxVersion()
    {
      return 0;
    }

    public KcpPassword(byte[] pbPasswordUtf8)
    {
      SetKey(pbPasswordUtf8);
    }

    public KcpPassword(string strPassword)
    {
      SetKey(StrUtil.Utf8.GetBytes(strPassword));
    }

    private void SetKey(byte[] pbPasswordUtf8)
    {
      Debug.Assert(pbPasswordUtf8 != null);
      if (pbPasswordUtf8 == null) throw new ArgumentNullException("pbPasswordUtf8");

#if (DEBUG && !KeePassLibSD)
      Debug.Assert(ValidatePassword(pbPasswordUtf8));
#endif

      byte[] pbRaw = CryptoUtil.HashSha256(pbPasswordUtf8);

      m_psPassword = new ProtectedString(true, pbPasswordUtf8);
      m_pbKeyData = new ProtectedBinary(true, pbRaw);
    }

    // public void Clear()
    // {
    //	m_psPassword = null;
    //	m_pbKeyData = null;
    // }

#if (DEBUG && !KeePassLibSD)
    private static bool ValidatePassword(byte[] pb)
    {
      try
      {
        string str = StrUtil.Utf8.GetString(pb);
        return str.IsNormalized(NormalizationForm.FormC);
      }
      catch (Exception) { Debug.Assert(false); }

      return false;
    }
#endif
  }
}
